Pilon Fractures Workup

Updated: May 20, 2019
  • Author: Vinod K Panchbhavi, MD, FACS, FAOA, FABOS, FAAOS; Chief Editor: Thomas M DeBerardino, MD  more...
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Workup

Laboratory Studies

If patients have preexisting conditions or comorbidities, then appropriate blood investigations are ordered.

Next:

Imaging Studies

Plain radiography

Plain radiographs, including anteroposterior (AP), mortise, and lateral views centered over the ankle, help provide an understanding of the fracture fragments and the pattern and facilitate the planning of treatment.

In addition to these radiographs, obtain full-length radiographs of the leg, including the knee and ankle, to help assess alignment and to rule out any other fractures in the limb.

Plain radiographs of the contralateral ankle help provide a template for reconstruction of the ankle. Other areas of the body, such as the spine in the case of a fall from height, [19] may require radiographic evaluation, depending on clinical findings.

Two fracture classifications are commonly used, both of them based on the fracture pattern seen on radiographs, the degree of comminution, and displacement of the fragments. [20, 21]

The Rüedi and Allgöwer classification is as follows:

  • Type A - These are simple cleavage-type fractures with little or no articular displacement (see the first and second images below)
  • Type B: With these, displacement of the articular surface occurs without comminution (see the third and fourth images below)
  • Type C: Intra-articular displacement occurs with marked comminution (see the fifth and sixth images below)
Low-energy pilon fracture in distal tibia with no Low-energy pilon fracture in distal tibia with no significant displacement.
Lateral view of pilon fracture. Lateral view of pilon fracture.
Low-impact pilon fracture with displacement but wi Low-impact pilon fracture with displacement but without significant comminution.
Lateral view of pilon fracture. Lateral view of pilon fracture.
Significant comminution and displacement of fractu Significant comminution and displacement of fracture fragments in pilon fracture.
Lateral view of pilon fracture. Lateral view of pilon fracture.

The Association for Osteosynthesis/Orthopaedic Trauma Association (AO/OTA) classification (part of a comprehensive classification of long-bone fractures and tibia, numbered 43) is as follows [22] :

  • Type A - These fractures are extra-articular and subcategorized as simple (A1), comminuted (A2), or severely comminuted (A3)
  • Type B - These fractures involve only a portion of the articular surface and a single column; subcategories include pure split (B1), split with depression (B2), and depression with multiple fragments (B3)
  • Type C - These fractures involve the whole of the articular surface; they may be categorized as a simple split in the articular surface and the metaphysis (C1), an articular split that is simple with a metaphysis split that is multifragmentary (C2), or a fracture with multiple fragments of the articular surface and the metaphysis (C3)

A type of pilon fracture that is associated with posterior disruption and instability is being recognized as a special entity. This type of pilon fracture requires posterior stabilization and is potentially associated with worse outcomes. Failure to identify this fracture pattern has led to poor clinical outcomes and persistent talar subluxation.

The purpose of a study by Klammer et al was to classify posterior pilon fractures into three primary categories by increasing degree of complexity, as follows [23] :

  • Type 1 fractures with a single medially based posterior malleolar fragment can be addressed through a posterolateral approach alone
  • Type 2 fractures, in which the posterior fragment is split with possible posteromedial comminution, may require an additional medial or limited posteromedial approach to assist in reduction and fixation of the posteromedial fragment or separate medial malleolar fracture
  • Type 3 fractures have the fracture line of the posterior malleolus exit the medial malleolus anterior to the posterior colliculus, and an additional anteromedial fragment is present; a medial approach is always necessary for reduction and fixation of the additional anteromedial fragment

Further investigations

Repeat radiographs after application of a spanning external fixator (traction radiographs) will yield a better understanding of the fracture pattern, fracture fragments, and fracture planes. This information is necessary for planning the surgical approach and achieving optimal implant placement and orientation of interfragmentary screws.

Computed tomography (CT) may be necessary in some cases where there is significant comminution or where percutaneous approaches are being planned. It is best obtained after the fracture is stabilized and spanned in an external fixator—a strategy summarized in the dictum "First span, then scan."

This strategy yields a better understanding of the fracture pattern, the degree of comminution, the displacement, and the impaction of articular fragments that may not be evident on plain radiographs. The degree of comminution may indicate severity of damage to articular surface and influence decision-making. This can be valuable in planning the operation (eg, by helping to determine the approach to the fragments and the orientation of the screws).

In a study by Misir et al, 20 orthopedic surgeons compared traction radiographs with CT scans in the evaluation of fracture morphology and consecutive treatment decisions in 12 OTA/AO 43C3 fractures. [24] Each observer was required to identify the anterolateral, posterolateral, and medial malleolus fragments and the lateral, central, and medial shoulder comminution zones. They then had to recommend treatment (nonoperative, open reduction and internal fixation [ORIF], closed reduction and external fixation, percutaneous screw fixation, or primary tibiotalar arthrodesis) with the best surgical approach (medial, anterolateral, posterolateral, posteromedial, or combined).

This study analyzed intra- and interobserver reliability, correct identification of fracture fragments and comminution zones on both images, and consistency of treatment recommendations and surgical approaches. [24] Treatment and surgical approach recommendations after traction radiographs and CT were similar. The authors concluded that traction radiographs may be a useful alternative to CT in the preoperative planning of pilon fracture repair. Despite less reliable fracture fragment and comminution zone identification on traction radiographs, treatment recommendations and surgical approach were not influenced.

Despite the variations in the mechanism of injury and in the degree or direction of the forces involved, tibial plafond fractures occur in consistent fracture patterns and in the following fracture fragments as a consequence of the presence of ligamentous attachments [25] :

  • Anterolateral or Chaput fragment – This fragment remains attached to the fibula through the anterior tibiofibular ligaments and rotated externally and or subluxed and displaced inferiorly; traction and spanning may help with reduction of the subluxation with the help of ligamentotaxis, but if not, the fragment should be manipulated into as nearly anatomic a position as possible to reduce tension over the soft tissues and to help with definitive reduction and fixation at a later stage
  • Anteromedial fragment – The size of the medial malleolar fragment varies, depending on the direction of forces; a spiral force or vertical force causes a large fragment; if there is addition of an angular or adduction force, there may be a separation of the anterior and posterior colliculus
  • Posterior malleolar fragment(s) – These can be posterolateral (Volkmann) or posteromedial or central; the posterolateral fragment is attached to the fibula with posterior tibiofibular ligaments, and the posteromedial fragments are attached to the deltoid ligament; a large posterior malleolar fragment signifies posterior instability
  • Central impaction – A purely vertical force can drive impacted comminuted fragments into the tibial metaphysis completely bereft of any soft-tissue attachments
  • Anterior impaction fragments – These occur when there is a dorsiflexion force; they tend to be multiple and have capsular attachments

Cole et al reported on fracture lines using axial CT scan images in 38 consecutive AO/OTA type 43C3 fractures. [25] For each fracture, a map of the fracture lines and zones of comminution was drawn. Each map was digitized and graphically superimposed to create a compilation of fracture lines and zones of comminution. On the basis of this compilation, major and minor fracture lines were identified and fracture patterns were defined. (See the image below.)

CT scan showing axial cut of pilon fracture. CT scan showing axial cut of pilon fracture.

Specifically, a basic Y pattern, constant across all patients, was identified where the stem of the Y went into the fibula incisura. All other fracture lines were considered secondary and these defined the comminution. One hundred percent of major fracture lines involved the tibiofibular joint and all exited medially in two general zones, anterior and posterior to the medial malleolus, best described as a Y-shaped pattern. Therefore, three main fragments existed in every single case. Comminution was present in 36 (95%) of 38 cases, and it was predominantly located centrally and in the anterolateral quarter.

Angiography is required if vascular compromise is suspected.

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